The present invention is directed to a hydraulic apparatus for generating impacts, commonly known as a hydraulic hammer and which is used especially in Civil Engineering.
Different types of hydraulic hammers are known which generally include an operating hydraulic having a plunger reciprocatingly movable therein, and a distributing or controlling member which does the same. Generally speaking, in the presently known hydraulic hammers, the working cylinder is made up of several actuating chambers, each having different inner diameters, such as are disclosed in British Pat. Nos. 1,161,445 and 1,160,270, and the plunger has, in correspondence with these chambers, cross-sectional sections with differing areas for closing, opening or connecting the said chambers with each other or to other elements in the apparatus. The differing areas provide different working areas upon which the hydraulic fluid can operate for causing the plunger to move. The variations in the inner diameters in the working chambers of the working cylinder results in a more complicated construction and makes the sealing between the chambers and guiding the plunger in its movement more difficult.
Further, the presently known hydraulic hammers do not include automatic stopping devices, or include only devices for manually starting or stopping the operation, such as the hydraulic hammers disclosed in British Pat. No. 1,161,445, already cited above, and No. 1,480,753, where, in the event that the operator becomes distracted, the apparatus can begin operation when the tool is not set against the workpiece and, since the apparatus is operating with no load, there is a danger of it being damaged.